I am sure it has happened at meetings I have been at. My thinking (and I am fairly new to AA, so please forgive as this is only my thinking here, but)...
It's a AA meeting. 98% of drunk people who would go to one are SEEKING HELP. Maybe they are bombed when the idea occurs to them. Maybe it is the sole 'moment of clarity' they had that day. Maybe they are normally great, awesome, SOBER people with months ro years under their belt and slipped that one time. They are drunk though, and hence they (like most of us/perhaps you) have virtually no control over their actions at that moment.
I, were it me, would take the person aside, and try to talk to them, during or after. If you or I did not feel comfortable at the time, I might- plotely and as gently as possible, just say it, out loud to the group, and perhaps someone else/a group of folks could do it for the poor man or woman struggling. Talking to them is certainly useful. Getting them home safe/to ER safe is as well. Understanding there is a darn good chance that tomorrow they won't remember much of what you said or did is probably a good thing to prepare yourself for too.
It's AA. The person is drunk, and almost certainly would prefer (in the long run, at least/for a moment) NOT to be, but can't control that right now, nor their actions.
That's just my .02 though.